Occurrence and Environmental Risk Assessment of Antibiotic Contamination in Urban Lakes of Hanoi, Vietnam

Antibiotic contamination in surface waters represents a growing environmental and public health concern, particularly in rapidly urbanizing regions. This study investigates the occurrence, concentration, and spatial distribution of selected antibiotics in surface water from eight urban lakes in Hanoi, Vietnam. Using LC-MS/MS analysis, we quantified nine commonly used antibiotics, including sulfonamides, fluoroquinolones, and trimethoprim. Sulfamethoxazole (SMX) was the most frequently detected compound, reaching concentrations up to 1619.35 ng/L, particularly in lakes receiving untreated municipal and healthcare wastewater. The environmental behavior of detected compounds varied according to their physicochemical properties: hydrophilic antibiotics remained in the water column, while fluoroquinolones accumulated in sediments and biota. Risk quotient analysis indicated moderate to high ecological risks for ciprofloxacin, ofloxacin, and SMX in several lakes. These findings provide critical baseline data for environmental risk assessment and underscore the need for stricter regulatory oversight and improved wastewater management to reduce antibiotic pollution and limit the development of antimicrobial resistance in urban aquatic environments.